1. You work for a company producing widgets on an assembly line. Each worker needs to produce at least 100 widgets per hour for the company to make a profit. A new piece of equipment is provided for the workers and a study is conducted to determine what effect it has on production. The study sampled 10 workers and obtained the following results:

_ ^

X = 108.3 S = 21.807

What type of statistical test should be performed? Why?

2. A highway engineer wants to install a new road surface on a stretch of highway that has produced a large number of accidents that are believed to be due to the road surface. Accident data were obtained for each of the 12 months before and each of the 12 months after the new road surface was installed.

(a) What is the research design for this study? WHY?

(b) What statistical procedure (test) should be used to determine if the new road surface has produced any change in the number of accidents?

3. What is the critical t value for determining the significance of a two-tailed (non-directional) one-sample t test with a = .05 and N = 15?